package com.cx.common.security;

import org.apache.commons.lang.StringUtils;

import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.DESKeySpec;
import java.security.MessageDigest;
import java.security.SecureRandom;

/**
 *
 * @Author:cxy
 * @Date:2019/10/24 15:11
 */
public class CryptUtils {

	private static final String PASSWORD_CRYPT_KEY = "r$1d9SA%";
	private final static String DES = "DES";

	/**
	 * MD5 摘要计算(byte[]).
	 * 
	 * @param src
	 *            byte[]
	 * @throws Exception
	 * @return byte[] 16 bit digest
	 */
	public static byte[] md5(byte[] src) throws Exception {
		MessageDigest alg = MessageDigest.getInstance("MD5");
		return alg.digest(src);
	}

	/**
	 * MD5 摘要计算(String).
	 * 
	 * @param src
	 *            String
	 * @throws Exception
	 * @return String
	 */
	public static String md5(String src) {
		try {
			return byte2hex(md5(src.getBytes()));
		} catch (Exception e) {
			return StringUtils.EMPTY;
		}
	}

	/**
	 * 加密
	 * 
	 * @param src
	 *            数据源
	 * @param key
	 *            密钥，长度必须是8的倍数
	 * @return 返回加密后的数据
	 * @throws Exception
	 */
	public static byte[] encrypt(byte[] src, byte[] key) throws Exception {
		// DES算法要求有一个可信任的随机数源
		SecureRandom sr = new SecureRandom();
		// 从原始密匙数据创建DESKeySpec对象
		DESKeySpec dks = new DESKeySpec(key);
		// 创建一个密匙工厂，然后用它把DESKeySpec转换成
		// 一个SecretKey对象
		SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(DES);
		SecretKey securekey = keyFactory.generateSecret(dks);
		// Cipher对象实际完成加密操作
		Cipher cipher = Cipher.getInstance(DES);
		// 用密匙初始化Cipher对象
		cipher.init(Cipher.ENCRYPT_MODE, securekey, sr);
		// 现在，获取数据并加密
		// 正式执行加密操作
		return cipher.doFinal(src);
	}

	public static byte[] hex2byte(byte[] b) {
		if ((b.length % 2) != 0) {
			throw new IllegalArgumentException("长度不是偶数");
		}
		byte[] b2 = new byte[b.length / 2];
		for (int n = 0; n < b.length; n += 2) {
			String item = new String(b, n, 2);
			b2[n / 2] = (byte) Integer.parseInt(item, 16);
		}
		return b2;
	}

	/**
	 * 解密
	 * 
	 * @param src
	 *            数据源
	 * @param key
	 *            密钥，长度必须是8的倍数
	 * @return 返回解密后的原始数据
	 * @throws Exception
	 */
	public static byte[] decrypt(byte[] src, byte[] key) throws Exception {
		// DES算法要求有一个可信任的随机数源
		SecureRandom sr = new SecureRandom();
		// 从原始密匙数据创建一个DESKeySpec对象
		DESKeySpec dks = new DESKeySpec(key);
		// 创建一个密匙工厂，然后用它把DESKeySpec对象转换成
		// 一个SecretKey对象
		SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(DES);
		SecretKey securekey = keyFactory.generateSecret(dks);
		// Cipher对象实际完成解密操作
		Cipher cipher = Cipher.getInstance(DES);
		// 用密匙初始化Cipher对象
		cipher.init(Cipher.DECRYPT_MODE, securekey, sr);
		// 现在，获取数据并解密
		// 正式执行解密操作
		return cipher.doFinal(src);
	}

	/**
	 * 密码解密
	 * 
	 * @param data
	 * @return
	 * @throws Exception
	 */
	public final static String decryptPassword(String data) {
		if (data != null) {
			try {
				return new String(decrypt(hex2byte(data.getBytes()), PASSWORD_CRYPT_KEY.getBytes()));
			} catch (Exception e) {
				e.printStackTrace();
			}
		}
		return null;
	}

	/**
	 * 密码加密
	 * 
	 * @param password
	 * @return
	 * @throws Exception
	 */
	public final static String encryptPassword(String password) {
		if (password != null) {
			try {
				return byte2hex(encrypt(password.getBytes(), PASSWORD_CRYPT_KEY.getBytes()));
			} catch (Exception e) {
				e.printStackTrace();
			}
		}
		return null;
	}

	/**
	 * 二行制转字符串
	 * 
	 * @param b
	 * @return
	 */
	public static String byte2hex(byte[] b) {
		return byte2hex(b, null);
	}

	/**
	 * 二行制转页面字符串
	 * 
	 * @param b
	 * @return
	 */
	public static String byte2webhex(byte[] b) {
		return byte2hex(b, "%");
	}

	/**
	 * 二行制转字符串
	 * 
	 * @param b
	 * @param elide
	 *            分隔符
	 * @return
	 */
	public static String byte2hex(byte[] b, String elide) {
		StringBuilder sb = new StringBuilder(b != null ? b.length << 1 : 0);
		String stmp = null;
		elide = elide == null ? "" : elide;
		for (int n = 0; b != null && n < b.length; n++) {
			stmp = (Integer.toHexString(b[n] & 0XFF));
			if (stmp.length() == 1)
				sb.append(elide).append("0").append(stmp);
			else
				sb.append(elide).append(stmp);
		}
		return sb.toString();
	}

	public static String getMD5(byte[] source) {
		try {
			return byte2hex(md5(source));
		} catch (Exception e) {
			return StringUtils.EMPTY;
		}
	}

}
